He is being cast by some journalists as a young champion of the First Amendment, jailed for taking a lonely stand against heavy-handed federal prosecutors.

Josh Wolf, a 24-year-old blogger, has spent more than six months behind bars in California -- the longest contempt-of-court term ever served by someone in the media -- for refusing to turn over a videotape he shot of a violent San Francisco demonstration against a Group of Eight summit meeting. Unless a mediation session today can break the impasse, he will likely remain imprisoned at least until the current grand jury's term expires in July.

"Even in high school, he was standing up for things that weren't considered popular," says his mother, Liz Wolf-Spada.

But Wolf's rationale for withholding the video, and refusing to testify, is less than crystal clear. There are no confidential sources involved in the case. He sold part of the tape to local television stations and posted another portion on his blog. Why, then, is he willing to give up his freedom over the remaining footage?

"It's one thing to say journalists must respect promises of confidentiality they made to their sources," says Eugene Volokh, a law professor at the University of California at Los Angeles. "It would be quite another to say journalists have a right to refuse to testify even about non-confidential sources. When something is videotaped in a public place, it's hard to see even an implied agreement of confidentiality."

In an interview with PBS's "Frontline," Wolf says: "There was a trust established between people involved in the organization that I was covering and myself . . . that what I chose to release was what I chose to release, and that I wasn't an investigator for the state."

Wolf taped the anarchists' San Francisco protest, against a G-8 summit meeting in Scotland, in July 2005. One police officer, Peter Shields, had his skull fractured by a hooded assailant with a pipe or baseball bat. Three people were charged in the attack. Police say protesters also put a mattress under Shields's police car and tried to set it on fire.

But in an unusual move, federal prosecutors took over the arson case from state authorities on grounds that San Francisco's police department receives funding from Washington. While there are no outward signs of an active probe, Luke Macaulay, a spokesman for the U.S. attorney in San Francisco, says that "the incident is under investigation so that the grand jury can determine what, if any, crimes were committed." He would not elaborate.

Martin Garbus, Wolf's attorney, says the police car received limited damage. He says Wolf "is staying in jail for close to 200 days so they can investigate who broke the taillight on a cop car." Garbus also questions why federal prosecutors are involved, adding Wolf might be protected under California's shield law for journalists if state authorities were handling the case. There is no federal shield law.

Garbus has offered to allow U.S. District Judge William Alsup to review the tape privately to buttress his client's contention that it contains only interviews with protesters who removed their masks, not evidence of a crime. Alsup, who has described Wolf as an "alleged journalist," declined.

Wolf was a student at San Francisco State who worked part time as an outreach staffer at a community college television station. He started a blog and occasionally sold videotape to news organizations.

"I would define a journalist as someone who brings news to the public," says Garbus, a noted First Amendment lawyer handling the case on a pro bono basis. "It's a definition that might cause journalists some discomfort because it opens up the gates."

But U.S. Attorney Kevin Ryan says in a court filing that Wolf's resistance "is apparently fueled by his anointment as a journalistic martyr" and that he needs "to come to grips with the fact that he was simply a person with a video camera who happened to record some public events."

The day after the protest, the San Francisco Chronicle reports, Wolf referred to himself on his Web site as an "artist, an activist, an anarchist and an archivist."

Wolf has repeatedly lost in the courts, with the U.S. Court of Appeals of the 9th Circuit upholding the grand jury subpoena for his testimony. The Reporters Committee for Freedom of the Press is among the groups that filed briefs on his behalf.

Wolf's case is the latest in a spate of prosecutions in which journalists have been threatened with imprisonment. Judith Miller, the former New York Times reporter who spent 85 days in jail for her initial refusal to testify in the Valerie Plame leak investigation, has embraced Wolf's cause. "Mr. Wolf is the latest addition to a club whose growing membership should trouble us all," Miller wrote in the New York Sun last year.

Two San Francisco Chronicle reporters, Lance Williams and Mark Fainaru-Wada, avoided jail last month for refusing to testify about how they got grand jury testimony involving allegations of steroid use by baseball stars. Their source, Troy Ellerman, a lawyer for an executive with the laboratory under investigation, was revealed when he pleaded guilty to contempt of court and obstruction of justice. The Chronicle has drawn some criticism for protecting Ellerman because he charged that prosecutors had leaked the testimony and said the publicity would deprive his client of a fair trial.

Wolf's case has attracted far less attention because he is not affiliated with any news outlet. Wolf-Spada, who says her son grew up with her in "a liberal Democratic household" after her divorce, urged members of Congress during a Washington visit to press the Justice Department to withdraw the subpoena.

"Truthfully, I don't think it's even about the tape or the police car," she says. "They want him to testify so they can develop a list of who protests in San Francisco."